1. Field of the Invention
This invention relates to a food sterilizing apparatus capable of successively carrying out steps of sterilizing and cooling food contained in rigid containers.
2. Prior Art
Conventionally, solid ingredients of nourishing preparations containing both solid and liquid such as stew and sold as preservable food in retort pouches are sterilized on a batch basis in sterilizing vessels before being retrieved for packaging. For example, Japanese Patent Publication No. 56-121468 discloses a sterilizing apparatus for producing sterilized solid food where granular solid food is mixed with liquid serving as a heat transmitting medium, heated, sterilized and then separated again from the liquid. However, the apparatus has drawbacks that it requires cumbersome operations of mixing solid with liquid before heating and sterilizing the food and pumping out the liquid after the completion of sterilization and that the solid food is liable to be broken as the container of the apparatus is rotated while the food is heated for sterilization.
Japanese Patent Publication No. 50-88251 discloses a sterilizing apparatus for sterilizing food in containers comprising a sterilizing chamber provided with inlet and outlet ports and a conveyor belt running through the inlet and outlet ports such that containers containing food are sequentially moved into the chamber by the conveyor belt and the food in the containers is heated and sterilized while moving in the chamber between the inlet and outlet ports. However, a major drawback of the apparatus is that the sterilizing chamber is not sealed and therefore the sterilizing effect of the apparatus is inevitably insufficient.
Japanese Patent Publication No. 49-71177 discloses a boiling/sterilizing apparatus comprising a boiler tank provided with an inlet air lock and an outlet air lock, a boiling/sterilizing chamber and an endless conveyor belt arranged below the boiling/sterilizing chamber. However, the apparatus has a major drawback that the sterilizing chamber cannot be sealed off for effective sterilizing operation because an endless conveyor belt is arranged inside the tank.
Japanese Patent Publication No. 51-42391 discloses a high temperature sterilizing apparatus comprising a vessel divided into a plurality of continuously arranged chambers, wherein any two adjacent chambers are separated from each other by a partition wall that can be moved for opening and closing. However, a major drawback of the apparatus is that a plurality of mutually independent conveyors have to be arranged within the each chambers to make the overall configuration of the apparatus rather complicated.
Japanese Patent Publication No. 5-30952 discloses a high temperature sterilizing apparatus comprising a heating/sterilizing chamber, a cooling chamber and an air blower arranged within a housing and an endless conveyor belt running through the chambers and the blower and extending to the outside of the housing. However, the apparatus has a major drawback that the heating/sterilizing chamber, the cooling chamber and the air blower cannot be efficiently designed because of the endless conveyor belt running therethrough.
In view of the above identified problems of existing food sterilizing apparatuses, the object of the invention is to provide a food sterilizing apparatus having a simple configuration and capable of completely and efficiently sterilizing food.